Ethanol Production May Consume Too Much Water

A new UF study raises concerns about ethanol's water demand in Florida. Four crops under consideration are very thirsty.

UF post-doctoral researcher Jason Evans (left) and professor Matthew Cohen say ramping up crop production for ethanol “would have significant impacts on both land use and water resources.” [Photo: Ray Carson]

From agricultural and energy company boardrooms to university laboratories, excitement is building over the potential for large-scale biofuel production in Florida. But a new study by forestry researchers at the University of Florida raises an important question: Does the state have enough water to supply thirsty energy crops? ››Read report here

Matthew Cohen, a professor in UF’s School of Forest Resources and Conservation, and post-doctoral researcher Jason Evans in the Department of Wildlife Ecology and Conservation analyzed energy and water impacts for four ethanol crops — corn, sugarcane, sweet sorghum and pine — in Florida and Georgia. Their study, published in Global Change Biology, found that all four yielded net energy; meaning they are viable for replacing fossil fuels. But it also concluded that ramping up production enough to meet U.S. Energy Independence and Security Act mandates for renewable fuels by 2022 “would have significant impacts on both land use and water resources.”

Estimated water requirements for sweet sorghum, the most water-efficient crop in the study, “would increase by almost 25% total freshwater withdrawals for all human uses reported in Florida and Georgia for 2000,” Cohen and Evans write. “Corn and sugarcane would require well over twice this water volume.” While pine is not irrigated, the study says large-scale pine biofuel production could have a critical impact on regional water supplies available for humans and nature because of accelerated evaporation.

Cohen says the message for Florida policy-makers is that “any debate about biofuels should be explicitly coupled with strategies for water and energy conservation.”